Office of Energy Efficiency and Renewable Energy

US. oi%ce buildings consume approximately 1.2 EJ (1.1 Quadrillion BTUS or Quads) of energy, 0.72 EJ (0.68 Quads) of which is associated with space heating, cooling, and ventilation. These estimates, and other analyses of energy consumption in oillce buildings, are based on building energy analysis programs such as DOE-2. These analyses have been helpful in identifying opportunities for energy efficiency, developing building energy efficiency standards and predicting future energy consumption levels. Although these programs contain sophisticated models of heat transfer and HVAC system performance in buildings, they are acknowledged to have shortcomings in accounting for the energy associated with building airflows, particularly infiltration of outdoor air through leaks in the building envelope. These airflows, and their dependence on weather and ventilation system operation, are more complex than the models used in these programs. The simple models of infWration, ventilation and interzone airflows that are used in these programs do not enable the analysis of the energy consumption wsociated with building airflow or the impact of options that may reduce this energy consumption, such as increased envelope airtightness or better control of ventilation system airflow rates. This repor